J. Brahms's Op. 38 (1865) and Op. 99 (1886) Sonatas, which are among the most important representatives of the chamber music sonata composing tradition for the cello and piano, seem to summarize the impacts of the change in habits of utterance, performance and listening in European musical culture after 1850s on the art of composing in music. In this study, the position of these works in the tradition of chamber music sonata composing for the cello and piano is reviewed in two phases: The emergence of the tradition of chamber music sonata composing for the cello and piano before Brahms in European musical culture and Brahms in the tradition of chamber music composing in the second half of the 19. Century. Throughout the study, the emergence of the performance practice tradition of the small instrumental groups since 17. Century is examined; the importance of Op. 38 and 99 Sonatas by Brahms in repertoire of the chamber music works written for the cello and piano within the process from the first representatives in which base instruments are used primarily in presenting thematic materials to the second half of the 19. Century is explained.